1. Field of the Invention
The present invention relates to a driver circuit for dot inversion of liquid crystals. More particularly, the present invention relates to a simplified driver circuit for dot inversion of liquid crystals.
2. Description of the Related Art
In general, a conventional flat panel display is operated to generate pixels by controlling a series of corresponding thin film transistors (TFTs) such that a LCD display can be controlled to display predetermined images. The conventional flat panel display has a plurality of gate driving lines connected with corresponding gates of the thin film transistors so as to control on/off operation of the thin film transistor.
FIG. 1 illustrates polarity diagrams of gates of liquid-crystal capacitors (i.e. CLC) in relation to corresponding sources in two frames when the liquid-crystal capacitors are charged in dot inversion of voltage polarity switching. Referring to FIG. 1, the two frames are a first frame (identified as Frame N) and a second frame (identified as Frame N+1). By way of example, each of Frame N and Frame N+1 has a series of gates (identified as Frame G1, G2, G3, G4, G5) and a series of signal sources (identified as S1, S2, S3, S4, S5). In FIG. 1, positive and negative of polarities are identified as “+” and “−”.
FIG. 2 shows conventional voltage waveforms of voltage dot inversion switching of two sources in operating dot inversion of liquid crystals. Referring to FIG. 2, the two sources (first source S1 and second source S2) are switched for dot inversion with respect to a ground line (i.e. common voltage “VCOM”), indicated by a dotted line, between a positive voltage “VP” and a negative voltage “VN” so that the corresponding liquid crystals can be dot-inverted.
In FIG. 2, a solid line represents the voltage waveform of the first source S1 while a dashed line represents the voltage waveform of the second source S2. A symbol “S1+” represents a section of the voltage waveform of the first source S1 when the voltage is positive, and a symbol “S1−” represents a section of the voltage waveform of the first source S1 when the voltage is changed to a negative and vice versa. Correspondingly, a symbol “S2−” represents a section of the voltage waveform of the second source S2 when the voltage is negative, and a symbol “S2+” represents a section of the voltage waveform of the second source S2 when the voltage is changed to a positive and vice versa.
In first dot inversion, as best shown in the left portion of FIG. 2, the voltage of the first source S1 drops from the positive voltage VP to the negative voltage VN, and the voltage of the second source S2 rises from the negative voltage VN to the positive voltage VP synchronously. Alternatively, in second dot inversion, as best shown in the middle portion of FIG. 2, the voltage of the first source S1 rises from the negative voltage VN to the positive voltage VP, and the voltage of the second source S2 drops from the positive voltage VP to the negative voltage VN synchronously. It is apparent from FIG. 2 that the voltages of the first source S1 and the second source S2 are repeatedly switched in the same manner for dot inversion of liquid crystals.
However, conventional driver circuits for dot inversion of liquid crystals are constructed from a great number of additional components or high voltage components. However, there is a need of improving a conventional driver circuit for dot inversion of liquid crystals for simplifying the entire structure, reducing dimensions and power consumption of the driver circuit.
The driver circuit for dot inversion of liquid crystals has been described in many Taiwanese patent application publications and issued patents, for example, including TWN patent appln. Pub. No. 200903428, TWN patent appln. Pub. No. 200848844, TWN patent appln. Pub. No. 200847116, TWN patent appln. Pub. No. 200839364, TWN patent appln. Pub. No. 200828214, TWN patent appln. Pub. No. 200816126, TWN patent appln. Pub. No. 200811796, TWN patent appln. Pub. No. 200736776, TWN patent appln. Pub. No. 200723232, TWN patent appln. Pub. No. 200703221, TWN patent appln. Pub. No. 200703222, TWN patent appln. Pub. No. 200639779, TWN patent appln. Pub. No. 200533990, TWN patent appln. Pub. No. 200527362, TWN patent appln. Pub. No. 200530999, TWN patent appln. Pub. No. 200529151, TWN patent appln. Pub. No. 200521931, TWN patent appln. Pub. No. 200527361, TWN patent appln. Pub. No. 200514010, and TWN patent appln. Pub. No. 200303003; and TWN patent issued Pub. No. I293449, TWN patent issued Pub. No. I292901, TWN patent issued Pub. No. I291157, TWN patent issued Pub. No. I291160, TWN patent issued Pub. No. I284880, TWN patent issued Pub. No. I269257, TWN patent issued Pub. No. I284878, TWN patent issued Pub. No. I269259, TWN patent issued Pub. No I253617, TWN patent issued Pub. No. I240108, TWN patent issued Pub. No. I224697, TWN patent issued Pub. No. 583630, TWN patent issued Pub. No. 581909, TWN patent issued Pub. No. 573291, TWN patent issued Pub. No. 571283, TWN patent issued Pub. No. 559753, TWN patent issued Pub. No. 543018, TWN patent issued Pub. No. 521241, TWN patent issued Pub. No. 525127, TWN patent issued Pub. No. 494383, TWN patent issued Pub. No. 486687, TWN patent issued Pub. No. 374861 and TWN patent issued Pub. No. 350063. Each of the above-mentioned Taiwanese patent application publications and issued patents is incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
Further, the driver circuit for dot inversion of liquid crystals has also been described in many U.S. patent application publications and issued patents, for example, including US20080297458, US20070139327, US20060187164, US20040189575, US20020084960, US20020075212, US20020050972 and US20020024482; and, U.S. Pat. No. 7,463,232, U.S. Pat. No. 7,450,102, U.S. Pat. No. 7,420,533, U.S. Pat. No. 7,079,100, U.S. Pat. No. 7,079,097, U.S. Pat. No. 6,980,186, U.S. Pat. No. 6,914,644, U.S. Pat. No. 6,891,522, U.S. Pat. No. 6,842,161, U.S. Pat. No. 6,784,866, U.S. Pat. No. 6,724,362, U.S. Pat. No. 6,593,905, U.S. Pat. No. 6,590,555, U.S. Pat. No. 6,566,643, U.S. Pat. No. 6,559,822, U.S. Pat. No. 6,549,187, U.S. Pat. No. 6,512,505, U.S. Pat. No. 6,424,328, U.S. Pat. No. 6,380,919, U.S. Pat. No. 6,320,566, U.S. Pat. No. 6,297,793, and U.S. Pat. No. 6,064,363. Each of the above-mentioned U.S. patent application publications and issued patents is incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
Yet further, the driver circuit for dot inversion of liquid crystals has also been described in many foreign patent application publications and issued patents, for example, including JP2007156382; KR20070051800, KR20040057248, KR20040048523, KR20040019708, KR20050015031, KR20050015030, KR20000007618, KR100242443, KR20030055921, KR20030055892, KR20030029698, KR20020058796, KR20020058141, KR20020052071, KR20020050040, KR20020046601 and KR20020017340. Each of the above-mentioned Intl. patent application publications and issued patents is incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
As is described in greater detail below, the present invention provides a driver circuit for dot inversion of liquid crystals. The driver circuit includes a single positive source and a single negative source to form two source-level outputs for positive and negative outputs. The driver circuit further includes selector circuits consisted of low voltage components in such a way as to mitigate and overcome the above problem.